This invention relates generally to wireless communication networks, and more particularly to roaming and handover from a Wideband Code Division Multiple Access (WCDMA) third generation (3G) network to a Two Generation (2G) network.
Wireless communication networks including fixed wireless and cellular-type mobile communications networks continue to evolve. There are several available technologies for providing wireless communications including Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Global System for Mobile Communications (GSM), Advanced Mobile Phone System (AMPS) and Digital AMPS (D-AMPS) (IS-136 TDMA). These networks continue to be deployed throughout the world. Many equipment suppliers currently manufacture these various systems and typically work through standards groups to ensure commonality and inter-operability of the various networks.
As wireless communications networks move into the 21 st century, a new type of wireless network is evolving currently known as Wideband Code Division Multiple Access (WCDMA) or Wideband Packet Code Division Multiple Access (WPCDMA) based third generation (3G) networks. These third generation wireless systems are slowly becoming a reality for Future Public Land Mobile Networks (FPLMNs). When 3G networks are implemented, service coverage may be implemented gradually, for example, by migrating slowly from 2G to 3G. Initially, 3G coverage may be limited, with a possibility of drop-outs due to lack of coverage in certain geographical locations. To prevent this, dual-mode wireless mobile terminals will be available that operate in both 2G and 3G systems.
There is a desire to intelligently handover and provide roaming from a 3G network to a 2G network, for example, when a 3G network becomes unavailable or is not accessible in a mobile user""s physical location.
The present invention achieves technical advantages as a method and node for providing handover and roaming of a wireless terminal from a 3G communication system to a 2G communication system, and further including a wireless communication terminal capable of the same. The present invention provides the ability of a dual-mode wireless terminal operating in a 3G communication system to obtain control channel information regarding a 2G communication system, and to switch service as a function of the control channel information received.
In one embodiment, disclosed is a method of supporting handover and roaming of a wireless terminal from a third generation (3G) communication system to a second generation (2G) communication system, comprising the step of providing control channel information for the 2G communication system over a downlink control channel of the 3G communication system to the wireless terminal.
In another embodiment, disclosed is a node in a third generation (3G) wireless communication network communicable with a wireless communication terminal, comprising a means to communication with the wireless communication terminal and a means providing control channel information of a second generation (2G) communication network over a downlink control channel at the 3G communication network.
Also disclosed is a wireless communication terminal, comprising a transceiver capable of communicating with a node of both a third generation (3G) wireless communication network and a second generation (2G) wireless communication network; and a control means coupled to the receiver for receiving and identifying control channel information indicative of the 2G communication network from a downlink control channel at the 3G communication network.
Advantages of the present invention include the prevention of drop-outs and faster switch-overs from a 3G network to a 2G network due to faster synchronization between networks. Rather than searching through 100-400 frequencies looking for a synchronization channel (SCH) burst in a 2G GSM network, a wireless mobile station is provided with the channel control information by the 3G network and thus finds the SCH in 1-10 tries, for example, reducing switch-over time 100-fold. Surge times of the wireless mobile station are improved with the present invention, resulting in increased efficiency, e.g., more bandwidth is allocatable for data transmission, and also resulting in power savings for the wireless mobile station, which is especially beneficial for battery-powered wireless mobile terminals.